[MC-105924] Spectral arrow doesn't show duration in the item's lore

The Bug

Unlike any potion, splash potion, lingering potion or tipped arrow (outside of the ones with instant effects), the spectral arrow shows no duration of the potion effect, nor that it gives an effect.

Steps to Reproduce

Give yourself a spectral arrow.
```
/give @s minecraft:spectral_arrow
```
Open your inventory and hold your mouse cursor over it to display the item's tooltip.
Look at the item's lore closely.

Observed Behavior

Spectral arrows do not display their potion effect along with its duration in its item's lore.

Expected Behavior

Spectral arrows would display their potion effect along with its duration in its item's lore.

Code Analysis

Code analysis by @unknown can be found in this comment.

Linked issues

relates to 1

MC-16204 Creative gui showing detailed effects does not show on some potions or bows Resolved

Attachments

2016-08-09 15_54_51-Minecraft 1.10.2.png

MC-105924.mp4

Comments 19

bemoty 2016-08-09T13:55:46Z

Can confirm.

bemoty 2016-08-13T00:27:08Z

Can confirm for 16w32b.

SLScool 2016-08-17T04:47:51Z

How does one get the title of Moderator or Helper?

SLScoolFriend 2016-08-17T04:49:11Z

I think the bug is not a bug, but simply how it's made. Spectral arrows are their own special arrow type (they're not tipped arrows), so you can't change the duration, nor can you change the effect (without commands).

And SLScool, is a bug report really the best place to ask that question?

SLScool 2016-08-17T04:54:17Z

Hobbit2469, I would say the same thing, except that I've been on the wiki, and I've seen many updates fix many bugs I never thought were issues, and I'll say the same thing about this one.

Also, do you know any better place to ask?

9 more comments

user-f2760 2016-08-17T09:18:30Z

@unknown: see this reddit post.

I reported this as an issue, since it can be considered an inconsistency; all other arrows that give potion effects that are not instant have a duration mentioned, while this one doesn't.

bemoty 2017-01-02T16:33:44Z

Confirmed for 1.11.2

JUE13 2017-04-09T08:02:30Z

Confirmed for 17w14a

bemoty 2017-08-03T19:31:20Z

The following is based on a decompiled version of Minecraft 1.12 using MCP 9.40-pre1.

So, I've been trying to find out what exactly is causing this and after playing around a bit with the code of spectral arrows in Minecraft, I found out that the answer is pretty simple: Unlike tipped arrows, spectral arrows don't have a potion effect applied to them directly, so the game doesn't know that it should display the effects which the spectral arrow is causing and their duration in the item lore. (Glowing; ID: 24)

While this might not be the best solution, I found a way to fix this issue. Eventually, the item lore of spectral arrows will look like this:

[media]

First, I registered "glowing" as a new PotionType in the net.minecraft.potion.PotionType.registerPotionTypes() method because it wasn't registered there already for some reason. To do that, I added the following line somewhere in the method body before the invocation of REGISTRY.validateKey().

public static void registerPotionTypes()
{
    ...
    registerPotionType("glowing", new PotionType(new PotionEffect[] {new PotionEffect(MobEffects.GLOWING, 1800)}));
    ...
    REGISTRY.validateKey();
}

I think most of this line should be self-explanatory. However, I'm a bit unsure about the second argument in the constructor call of net.minecraft.potion.PotionEffect, a signed integer. The argument name says "durationIn", I don't exactly know what the default duration of a spectral arrow's glowing effect is though. In the class net.minecraft.entity.projectile.EntitySpectralArrow there is a private integer called "duration" with the default duration value of the potion effect applied to every entity hit by a spectral arrow. In the method declaration of arrowHit(...) in the same class the potion effect is indeed applied for the duration saved in this variable. However, if I use 200 instead of 1800 as the "durationIn" in the constructor call of net.minecraft.potion.PotionEffect, I get a duration of "0:01", which is—of course—not correct. So after a few tests 1800 just seemed like the most appropriate value for me.

The second thing I did was to copy the addInformation(...) method declaration in the net.minecraft.item.ItemTippedArrow class and paste it into the net.minecraft.item.ItemSpectralArrow class. I then added another line of code which adds the "glowing" potion effect to the ItemStack.

public void addInformation(ItemStack stack, @Nullable World playerIn, List<String> tooltip, ITooltipFlag advanced)
{
    PotionUtils.addPotionToItemStack(stack, PotionType.getPotionTypeForName("glowing"));
    PotionUtils.addPotionTooltip(stack, tooltip, 0.125F);
}

Since the spectral arrow is an extra item and can only have one potion effect, I think it's completely fine to add the potion effect in this "hotfix style". But, welp, very likely there is much more to consider than I know about. ^^ I hope this short code analysis helps though. 🙂

bemoty 2017-08-12T23:46:16Z

Can confirm for MC 1.12.1.